Liquid fuel injection pumps



Dec. 15, 1964 K. F. HUTCHEON 3, 1

LIQUID FUEL INJECTION PUMPS Filed Sept. 10, 1962 United States Patent Ofiice 3,161,133 Patented Dec. 15, 1964 3,161,133 LIQUID FUEL INJECTION PUMPS Keith Finer Hutcheon, Denham, England, assignor to C.A.V. Limited, London, England Filed Sept. 10, 1962, Ser. No. 222,335 2 Claims. (Cl. 103-2) This invention relates to liquid fuel injection pumps for internal combustion engines, and of the kind comprising in combination a rotary distributor driven by the engine, a feed pump at one end of the distributor, a head at the other end of the distributor, said head having therein a transversely extending bore, at least one plunger in said bore, a governor-controlled throttle valve through which the feed pump supplies fuel intermittently as the distributor rotates to the bore in the head so as to move the plunger outwardly, and an annular cam surrounding the head and adapted to impart inward movements to the plunger as the head rotates and thereby deliver fuel through a passage in the distributor to the engine cylinders in turn.

According to the invention, a pump of the kind specified includes in combination an extension of the distributor at said one end thereof, an axial bore in said extension, a plunger in said bore, a flow path interconnecting the inlet and outlet of the feed pump so as to limit the output pressure of the latter, said flow path extending through the plunger and the arrangement being such that axial movement of the plunger serves to restrict the flow path, and centrifugally operable means secured to said extension for moving the plunger to restrict said fiow path by an amount dependent on the speed of the engine, so that the maximum permitted output pressure of the feed pump increases with engine speed.

The accompanying drawing is a sectional side view illustrating one example of the invention.

Referring to the drawing there is provided a body 1 which at one end contains a feed pump 2 of the kind comprising a rotary impeller provided with vanes.

At the other end of the body is contained a fuel injection pump comprising a rotary head 3 formed at one end of a distributor 4 serving to interconnect the rotary parts of the feed and injection pumps. In the head 3 is a transverse bore containing a pair of reciprocatory plungers 5 which through rollers 6 at their outer, ends cooperate with a surrounding annular cam 7.

Fuel from the feed pump is fed through a passage 8 in the body to an annular groove 9 in the periphery of the distributor 4 and thence by way of a throttle valve 10 to a further passage 11 in the body 1 which registers in turn, as the distributor rotates, wtih a plurality of radially opposed passages 12 in the distributor. The passages 12 are in communication with an axial passage 13 in the distributor which opens at one end into the bore in the head 3. Also leading from the axial passage in the distributor is a radial passage 14 which is adapted to register in turn, as the distributor'rotates, with a plurality of passages 15 in the body part which are adapted for connection to the injection nozzles of the engine cylinders.

The pump so far described is well known and operates in the'following manner. Fuel from the feed pump 2 is fed intermittently by way of the throttle valve 16 to e the passage 13 and thus serves to move the plungers 5 of the injection pump outwardly. At appropriate instants in the cycle the plungers 5 are moved inwardly by the action of the cam 7, and thereby serve to discharge fuel in turn to the engine cylinders.

If desired, the pump may also include means 16 operable by the output pressure of the feed pump for adjust ing the angular setting of the cam 7, whereby to vary the timing of the pump with engine speed.

At said one end of the distributor is an integral or separately formed extension 21 to which is secured a centrifugally operable means comprising a pair of pivotal Weights 22 movable outwardly by centrifugal forces as the distributor rotates. The weights are linked to a plunger 23 slidable in a bore 25 formed in an insert 41 forming part of the extension, so that the position of the plunger in the bore is dependent on the speed of the engine. A spring 24 is provided for assisting the action of centrifugal force, thereby preventing the permissable output pressure of the pump from becoming too low at low speeds.

The bore 25 communicates through annular grooves 26, 27 with passages 28, 29 in the extension 21, the passages 28, 29 being in communication respectively with the inlet 30 and outlet 31 of the pump 2. By restricting the flow path between the inlet 30 and outlet 31, the plunger 23 acts in the manner of a relief valve to determine the maximum permitted output of the pump. Moreover, axial movement of the plunger with increasing speed further restricts the flow path between the inlet 30 and outlet 31 to increase the permitted output pressure of the pump 2. Since the centrifugally operable means determines the axial position of the plunger, the maximum output pressure of the feed pump will increase with engine speed when the speed decreases the weights are moved inwardly by the pressure of fuel in the bore 25.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injection pump for an internal combustion engine, comprising in combination a rotary distributor adapted to be driven by the engine, a feed pump at one end of the distributor, said feed pump having an inlet and an outlet, a head at the other end of the distribu-tor, said head having therein a transversely extending bore, at least one plunger in said bore, a governorcontrolled throttle valve through which the feed pump supplies fuel intermittently as the distributor rotates to the bore in the head so as to move the plunger outwardly, an annular cam surrounding the head and adapted to impart inward movements to the plunger as the head rotates and thereby deliver fuel through a passage in the distributor to the engine cylinders in turn, an extension of the distributor at said one end thereof, an axial bore in said extension, a flow path interconnecting the inlet and outlet of the feed pump, said flow path extending through said bore, a plunger slidable in the bore and serving to restrict the flow path by an amount dependent on the axial position of the plunger, so that the maximum output pressure at which the feed pump supplies fuel to said'head as determined by the position of the plunger, and centrifugally operable means secured to said extension for moving the plunger to restrict said flow path by an amount dependent on the speed of the engine, .so that said maximum output pressure of the 3 feed pump increases with the speed of rotation of said distributor.

2. A liquid fuel pump as claimed in claim 1 including a spring for assisting the action of centrifugal forces, thereby preventing the permissible output pressure of 5 the feed pump from becoming too low at low speeds.

References Cited in the file of this patent UNITED STATES PATENTS 271,288 Wells Jan. 30, 1883 10 Lathrop Mar. 6, 1894 Reggio Mar. 9, 1943 Wheeler July 14, 1953 Roosa Apr. 28, 1959 Volossevich Sept. 19, 1961 Kemp et al. May 22, 1962 FOREIGN PATENTS Russia Mar. 2, 1959 

1. A LIQUID FUEL INJECTION PUMP FOR AN INTERNAL COMBUSTION ENGINE, COMPRISING IN COMBINATION A ROTARY DISTRIBUTOR ADAPTED TO BE DRIVEN BY THE ENGINE, A FEED PUMP AT ONE END OF THE DISTRIBUTOR, SAID FEED PUMP HAVING AN INLET AND AN OUTLET, A HEAD AT THE OTHER END OF THE DISTRIBUTOR, SAID HEAD HAVING THEREIN A TRANSVERSELY EXTENDING BORE, AT LEAST ONE PLUNGER IN SAID BORE, A GOVERNORCONTROLLED THROTTLE VALVE THROUGH WHICH THE FEED PUMP SUPPLIES FUEL INTERMITTENTLY AS THE DISTRIBUTOR ROTATES TO THE BORE IN THE HEAD SO AS TO MOVE THE PLUNGER OUTWARDLY, AN ANNULAR CAM SURROUNDING THE HEAD AND ADAPTED TO IMPART INWARD MOVEMENTS TO THE PLUNGER AS THE HEAD ROTATES AND THEREBY DELIVER FUEL THROUGH A PASSAGE IN THE DISTRIBUTOR TO THE ENGINE CYLINDERS IN TURN, AN EXTENSION OF THE DISTRIBUTOR AT SAID ONE END THEREOF, AN AXIAL BORE IN SAID EXTENSION, A FLOW PATH INTERCONNECTING THE INLET AND OUTLET OF THE FEED PUMP, SAID FLOW PATH EXTENDING THROUGH SAID BORE, A PLUNGER SLIDABLE IN THE BORE AND SERVING TO RESTRICT THE FLOW PATH BY AN AMOUNT DEPENDENT ON THE AXIAL POSITION OF THE PLUNGER, SO THAT THE MAXIMUM OUTPUT PRESSURE AT WHICH THE FEED PUMP SUPPLIES FUEL TO SAID HEAD AS DETERMINED BY THE POSITION OF THE PLUNGER, AND CENTRIFUGALLY OPERABLE MEANS SECURED TO SAID EXTENSION FOR MOVING THE PLUNGER TO RESTRICT SAID FLOW PATH BY AN AMOUNT DEPENDENT ON THE SPEED OF THE ENGINE, SO THAT SAID MAXIMUM OUTPUT PRESSURE OF THE FEED PUMP INCREASES WITH THE SPEED OF ROTATION OF SAID DISTRIBUTOR. 